Struct MetadataOnlyOutcome 

#[non_exhaustive]
pub struct MetadataOnlyOutcome {
    pub source: String,
    pub resolver_profile: String,
    pub license: Option<String>,
    pub oa_url: Option<String>,
    pub oa_status: Option<String>,
    pub metadata: Value,
    pub metadata_quality: Vec<String>,
    pub repaired_fields: BTreeMap<String, String>,
}

Outcome of a successful metadata_only call.

Mirrors the wire shape documented in docs/MCP_TOOLS.md §11: the source identifies which resolver produced the metadata, license is the OA license string when known (Unpaywall channel), oa_url is the discovered OA URL (never followed by this orchestrator), and metadata is the source’s native JSON payload (Crossref message, Unpaywall work record, or the parsed arXiv Atom-feed object).

metadata is serialized as-is by the MCP envelope builder (crates/doiget-mcp/src/lib.rs); we deliberately do NOT normalize here so the agent can see exactly what the source returned.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

source: String

Resolver key that produced the metadata payload. One of "crossref", "unpaywall", "arxiv" (the closed set named in docs/MCP_TOOLS.md §11 type alias).

resolver_profile: String

Resolver profile under which the canonical-digest (ADR-0021 §1) was minted for this call. In Slice 4 this equals Self::source verbatim (the metadata-only path emits one row per consulted resolver); future slices that introduce overlapping resolvers MAY have resolver_profile != source. Surfaced through the doiget_metadata_only MCP envelope per ADR-0021 §4.

license: Option<String>

OA license string when the resolver could supply one (today only the Unpaywall fallback path populates this). None when the primary source did not surface a license.

oa_url: Option<String>

Discovered OA URL — surfaced to the caller for separate action, never followed by this orchestrator. The Crossref response’s message.link[] array is mined first; the Unpaywall fallback path uses best_oa_location.url_for_pdf (or url).

oa_status: Option<String>

Open-access status for the ref, when known (#281 item 4): the Unpaywall classification gold / green / hybrid / bronze / closed, or "green" for an arXiv ref. None when the resolver that answered did not surface it — notably the Crossref-first metadata path, which does NOT consult Unpaywall unless Crossref fails, so a None here means “not determined”, not “no OA”. #[serde(default)] keeps older resolver_cache entries (written before this field existed) readable.

metadata: Value

Source’s native metadata payload. For Crossref this is the message object; for Unpaywall the work record; for arXiv the parsed Atom-feed JSON (see crate::sources::arxiv::parse_atom_feed).

metadata_quality: Vec<String>

Quality flags on what metadata_only_to_store wrote, e.g. replacement_char:venue for a field that still carries a U+FFFD (#608). metadata above stays the resolver’s payload as received, so this – with repaired_fields – is how a caller learns the stored entry differs from it. Empty from the pure resolvers, which store nothing.

repaired_fields: BTreeMap<String, String>

Fields metadata_only_to_store repaired from another enabled source before writing, field -> source key (#608).

Trait Implementations

impl Clone for MetadataOnlyOutcome

fn clone(&self) -> MetadataOnlyOutcome

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MetadataOnlyOutcome

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for MetadataOnlyOutcome

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for MetadataOnlyOutcome

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.